Troubleshooting A Dometic Gas And Electric RV Water Heater That Won't Operate

Question:

Had a new Dometic 6 gallon water heater professionally installed in our 1998 Sunnyside 26FK. It worked great while on propane but it wouldnt heat the water when running on electricity. After two days of us having plenty of hot water and without changing anything plus we were in a full hook-up RV Park, the heater stopped working even while on propane. What would cause it to stop working completely? The trailer has two 20 gallon propane tanks and both were at least 3/4 full and we were able to use our stove with no problems so is there something that needs to be reset. Thank you for your assistance in this frustrating matter...

asked by: Ed

Expert Reply:

The Dometic RV Water Heater # DMC74FR uses both gas and electric to properly operate. The electric heating element just assists to make it heat water faster but the main power source is going to be the gas. If your regulator is failing or needs to be readjusted it could be restricting the pressure and cause the heater to malfunction.

My first recommendation would be to cut the power to the unit and leave it off for 5 minutes to fully power down. Afterwards you can power it back up and if it's still malfunctioning then the next step would be to check the gas pressure, the voltage running to the unit, and the water pressure.

This unit requires 120v AC current to properly operate. If you use a multimeter # PT89ZR and prick into the wiring and get less than 120v then we know this is the issue and you'll have to trace through your wiring to find any damage/kinks/shorts and repair.

To check the gas you'll need a licensed technician to check the pressure with a meter. This is not something you'll be able to do yourself. This unit requires 10 - 13 W.C. to operate.

Water heaters typically require a water psi rating from 40-60psi to properly operate so the # A01-1124VP will help regulate your water pressure to a compliant rating.

If you continue to have issues please let me know and we can continue to troubleshoot.